1. Field of the Invention
The invention relates to a shut-off device comprising a housing which is to be connected to an adjacent conduit in a pressure-tight manner. In such a shut-off device a tubular passage is defined in the housing for a medium flowing through the conduit. Said device also comprises at least one sealing body which can be displaced by an articulated mechanism, by means of an adjusting drive that can be moved vertically in relation to the direction of flow, from an open position into a closed position in which the sealing contour of the at least one sealing body comes into contact with the tubular passage in a radially sealing manner. The articulated mechanism comprises a bearing body on which the at least one sealing body is pivotably positioned whereby the bearing body is moved into the housing.
2. Background of the Invention
Shut-off devices are known from WO 2003/100302 A1 and are usually made from metal or plastics. Devices made from thermoplastic material have the advantage that the individual housing parts can be joined using relevant materials while employing commonly used welding methods. A joint can also easily be made to an existing PE conduit network. In WO 2003/100302 A1 it is preferable that a cleaning scraper can run through the shut-off device. For this purpose the at least one sealing body is in the open position while arranged outside the conduit.
While in the operating state, axial forces form in the direction of the flow of the medium which must be withstood by either the sealing body or the adjusting drive. There is, on the one hand, a static strain in the closed position of the device when one-sided pressure forces occur and, on the other hand, also a dynamic strain in the open position when the sealing body is in an intermediate position or when the sealing body is the position shortly prior to the closing of the device.
Therefore it is suggested in DE 11 09 972 to move the articulated mechanism parallel to the moving direction of the adjusting drive. U.S. Pat. No. 3,119,594 A describes the guiding of the sealing body.